Locally, the mourning continues at Boston University a week after a 23-year-old graduate student was struck by a truck while riding his bike to class. Christopher Weigl was the second BU cyclist killed this fall.

A local engineer and Boston University graduate believes he might have a solution that would save lives.

When you hear a horn it usually gets a reaction. So engineer Jonathan Lansey came up with the idea of a bike horn.

"The first reaction is for people to brake. They stop immediately what they were doing even before looking to see where the sound is coming from. It's a reflex to respond to a honk," he said.

Lansey designed the horn so it wouldn't interfere with braking. The button is right where the thumb would be. He's marketing the product under the name "Loud Bicycle."

He got the idea after a friend was involved in a crash. She survived. But he's watched in horror as crash after crash has taken the lives of local cyclists. From January to mid-November, Boston EMS has responded to 579 bicycle-related incidents, up from 548 during the same time period in 2011. Five cyclists have been killed so far this year in Boston.

The most recent death of Wiegl really motivated the horns inventor to get it out quickly. He said he believes that death was preventable.

"A truck turned right into a bicycle. With a horn they would stop. I've experienced this. I've been using this for the last 9 months," said Lansey.

As a small operation, Loud Bicycle isn't sold in stores yet. Lansey put a video on Kickstarter.com which allows him to take pre-orders and make sure there's interest before mass producing the $95 horn. So far reaction has been good. But some worry the price tag may turn off some cyclists.

"I think anything that can get motorists to notice bicyclists more is a good thing. I encourage the inventor to keep at it. But make it smaller and less expensive so more people can have access to it," said David Watson of MassBike.

As for drivers who might be confused or annoyed when they realize that honking noise is actually coming from a two-wheeler?

"I'd rather face an angry driver than a kind EMT," said Lansey.

MassBike said not enough cyclists follow other safety measures. He stressed the importance of wearing reflective clothing and using bike lights.

Lawyers for Boston Marathon bomber Dzkokhar Tsarnaev rested their case in his federal death penalty trial Tuesday after presenting a brief case aimed at showing his late older brother was the mastermind of the 2013 terror attack.